An organic EL (electroluminescence) display device includes pixels provided in a matrix on each of display regions, an organic EL layer being formed in each of the pixels, and the organic EL (electroluminescence) display device makes the organic EL layer emit light to display an image.
In an organic EL display device displaying in full color, organic EL layers emitting light of red (R), green (G), and blue (B) colors are typically formed in each pixel. For this reason, the organic EL layers are formed into a pattern on a prescribed pixel for each light emission color by vapor deposition using a vapor deposition mask (hereinafter, may be referred to as selective coating deposition in some cases).
A method for depositing such organic EL layers on a vapor deposition target substrate is roughly classified into a method in which a relative position between a vapor deposition mask and a vapor deposition target substrate is fixed for vapor deposition as described in PTL 1, and a scan vapor deposition technique in which a vapor deposition target substrate relatively moves with respect to a vapor deposition mask for vapor deposition.
In the former method in which a relative position between the vapor deposition mask and the vapor deposition target substrate is fixed for the vapor deposition, the vapor deposition mask having almost the same area as the vapor deposition target substrate or having a certain area size, even though the vapor deposition mask does not have almost the same area as the vapor deposition target substrate. Therefore, as the vapor deposition target substrate is larger in size, the vapor deposition mask is also larger in size. As the vapor deposition mask is larger in size, deformation under its own weight or elongation due to heat is increased to readily cause a misalignment of a vapor deposition position or mixing of colors. This makes it difficult to enable high definition.
Hence, as a method for depositing organic EL layers on the vapor deposition target substrate, scan vapor deposition has attracted attention.
FIG. 17 is a perspective view illustrating a configuration of a vapor deposition device in the related art. As illustrated in FIG. 17, a vapor deposition device 101 includes a vapor deposition source 102, a vapor deposition mask 110 located above the vapor deposition source 102, and a substrate tray 120 movable along a rail 103. A direction along which the rail 103 extends is referred to as X-axis direction.
The vapor deposition mask 110 includes mask frame parts 110a and a mask body part 110c, ends of which are held by the mask frame parts 110a. The mask body part 110c includes vapor deposition regions 111 aligned in Y-axis direction perpendicular to X-axis direction. In each vapor deposition region 111, multiple slits 111a each corresponds to a width of a pixel formation region for any of red, green, or blue in the vapor deposition target substrate.
On the vapor deposition source 102, an emission outlet 102a is formed for emitting vapor deposition particles that are filled in the vapor deposition source 102.
FIG. 18 is a diagram illustrating a state where vapor deposition is started in the vapor deposition device of the related art. As illustrated in FIG. 18, a vapor deposition target substrate 130 is placed on the substrate tray 120 in such a way that a vapor deposition target surface 130a on which display regions 131 are formed in a matrix faces toward the vapor deposition source 102 and a rear surface 130b on the other side of the vapor deposition target substrate 130 faces upward.
The substrate tray 120, on which the vapor deposition target substrate 130 is placed, travels along the rails 103 in a direction illustrated by an arrow X1 (scanning direction), and the vapor deposition target substrate 130 is scanned. The vapor deposition particles are emitted from the emission outlet 102a on the vapor deposition source 102 in Z-axis direction (axis perpendicular to X-Y plane), and then the vapor deposition particles are deposited on the vapor deposition target surface 130a of the vapor deposition target substrate 130 through the slits 111a. 